I have a very large fern that someone smuggled to Canada from Brazil;
Also several Kangaroo ferns. Question: When should I bring them in
from the covered porch. Temps here at night are about 13 C. at
present.

Kangaroo ferns (Microsorium diversifolium or whatever their more recent
name is) come from a range of climatic conditions. Those from the
Canberra region are frost and even snow hardy (down to perhaps -5 deg C:
I've seen them growing at 1000 meters alt. in an exposed area adjacent
to a creek), but similar ferns from the Sydney region are probably a lot
more frost tender, so any suggestion of frost should see them indoors,
to be safe.